This invention relates to tire molds and especially to tire molds having heat pipes incorporated for providing improved heating of the tread and sidewall forming surfaces.
Tire molds of steel or aluminum have been heated by steam heated platens or by placing the molds in steam domes. Thermal conduction through steel or aluminum has been relied upon to transfer heat to the tread and sidewall forming surfaces. Also, the cure time has been extended by the temperature recovery time following a loading or unloading cycle. Problems have also been encountered in providing temperature uniformity at positions on the mold-tire interfaces.
The present invention is directed to utilizing a heat transfer system containing elongated sealed metal heat transferring heat pipes incorporated in the tire mold for transmitting heat to the mold surfaces. In accordance with this system, the heat is transmitted directly from the heat source such as a platen or a steam dome to the tread area of the mold. With a platen-heated mold, the heat pipes are positioned in the tread mold segments so as to transmit the heat from the platen directly to positions adjacent the tread forming surfaces of the mold. With the steam dome tire presses, the heat is transmitted by heat pipes directly from the steam dome to the heating positions adjacent the tread and sidewall forming surfaces of the mold.
In accordance with one aspect of the invention, there is provided a generally cylindrical tire mold having a radially inner tread forming surface, characterized by tubes extending from openings in the mold to heating positions adjacent the tread forming surface and heat pipe means positioned in the tubes for selectively transferring heat to the tire mold at the heating positions.
In accordance with another aspect of this invention there is provided a tire mold an upper cylindrical mold half and a lower cylindrical mold half with each mold half having a cylindrical groove spaced from the tread forming surface, the heat pipe means comprising a coiled heat pipe disposed in the groove and the tubes being formed in the groove by heat conducting material filling the voids around the heat pipe.